By Michael Petroff
Battalion chief/training officer (ret.)
Exhaust removal systems help to create a safer environment for firefighters in confined environments by protecting them from noxious vehicle exhaust. According to NIOSH, studies show that an "occupational carcinogenic hazard exists in human exposure to diesel exhaust."
There are two types of exhaust systems available to fire departments: direct source capture systems and filtration systems. The direct source capture systems are categorized into two sub categories: exhaust evacuation systems and direct source filtration systems.
Here are the main things you should know about these systems in order to help you make an informed purchasing decision.
Exhaust evacuation systems
These consist of control panel, a track-mounted hose and cables, an exhaust fan and ducting. The system attaches directly to the tailpipe, thereby capturing all exhaust emissions and carrying them out of the building via a fan and duct system.
Manufacturers employ several methods to attach the hose to the exhaust pipe. One uses an inflatable "boot," another a magnetic attachment system. Systems employ automatic start controls. When a vehicle is started, the system runs for a predetermined time. The automatic timer can be overridden when performing maintenance. When the vehicle leaves the station, the track-mounted hose follows the vehicle for a time. At the threshold, a release mechanism disconnects the hose from the vehicle. The system then retracts the hose.
Requirements of the systems include adequate electrical power (amperage and electrical phase capability) and a duct to the exterior of the building to vent the exhaust. Consideration should be given to the location of this discharge point regarding neighboring occupancies and intake points of a breathing air system if located in the same station. Inline particulate filters are available to remove the carbon soot before it is discharged into the outside air. The system that employs an inflatable boot requires an adequate supply of compressed air to inflate it. Modifications to vehicle tailpipes may be needed for proper attachment of the hose.
When operational procedures are followed for attachment of the systems, especially if the vehicle backs into the station, firefighters attaching the systems will not be exposed to diesel exhaust. Remember that backing spotters are necessary any time a vehicle is moving in reverse.
Vehicle-mounted filtration systems
This system consists of a filter diverter, filter and an electronic control unit. The system automatically operates for 10-99 seconds after the vehicle starts. This time is adjustable to suit the department’s needs and allows the vehicle to leave the station. The system also activates when the vehicle is in reverse gear. After the vehicle is shifted out of reverse gear, the system will continue in the filter mode for the pre-set time allowing the vehicle to back into the building and shut it off. Modifications must be made to the vehicle exhaust system.
These are sometimes referred to as "hoseless" systems and are mounted to the ceiling. Harmful exhaust components are forced through a series of three disposable filters. (Some filtration units also have a fourth-stage photo-catalytic oxidizer for germicidal protection.) The filters trap certain particles and chemically absorb other diesel exhaust components. The system automatically activates through a system of door switches or electric eyes that detect vehicle movement. The system then runs for a period of 12-15 minutes. Filtration systems involve the least amount of work necessary to install an exhaust removal system. No vehicle modification is needed and only an electrical power source and ceiling mounting space are needed in the fire station.
The Environmental Protection Agency (EPA) 2007 Highway Diesel Rule (EPA07) requires a reduction in the diesel particulate matter and nitrous oxide in diesel exhaust emission. This requirement is addressed by the use of an exhaust system component known as an "After-Treatment Device" (ATD). The majority of ATDs are either a diesel oxidation catalyst (DOC) or a diesel particulate filter (DPF).
Manufacturers of exhaust extraction systems and vehicle-mounted filtration systems are well aware of EPA07. They have adapted their products to work with the vehicle changes necessary to meet EPA07. Issues regarding exhaust temperatures during "regeneration" of the ATDs have been addressed.
Regeneration is a process to eliminate particulate matter in the ATD. It is recommended that this regeneration process be conducted outside of the fire station. EPA07 does not address issues relevant to diesel exhaust indoors; however, NFPA Standard 1500 and most building codes do. Therefore, a vehicle exhaust extraction or filtration system is highly recommended to protect firefighters from the risk of exposure to harmful diesel exhaust emissions.
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Michael Petroff is a retired battalion chief from the Ferguson Fire Department of St. Louis County, Missouri. BC Petroff served for more than 32 years, progressing through the ranks. He served on the St. Louis County Overhead response team, and is an instructor for national, state and local fire agencies. BC Petroff is a former western region director for the Fire Department Safety Officers Association, a member of the National Fire Protection Association 1021 Committee, a member of the Thomson Delmar Fire Advisory Board, and serves as the region VII regional advocate for the Everyone Goes Home Life Safety Initiatives Program.